Titanium base alloys



United States Patent Ofitice 3,184,305 Patented May 18, 1965 3,184,305 TETANKUM BASE ALLOYS I Sidney W. Poole and John Savas, Canton, Ohio, assignors This invention relates to titanium base alloys. More particularly, this invention relates to titanium base alloys having improved physical and mechanical properties. Still more particularly, this invention relates to titanium base alloys having excellent forgeability, good rollability, low yield in the solution treated condition, and other desirable physical properties. In addition, the alloys of this invention have low solution treating temperatures (1500 F.l57 5 P.) which vary in this range depending on section size. The alloys, moreover, are capable of solution treatment by air cooling from these desired low solution annealing temperatures. This is particularly advantageous from a production heat treating standpoint as the use of water quenching techniques during solution treating results in warpage of the materials being so treated. In accordance with one embodiment, this invention is further directed to titanium base alloys having excellent high temperature properties such as improved high temperature tensile and creep properties.

Titanium metal, because of its relatively low density and special high strength and high temperature properties, has been proposed for many uses and in alloys wherein satisfactory performance under high temperature conditions is an important or governing factor. Unfortunately, however, for certain special uses titanium metal and titanium base alloys have not been completely satisfactory. For example, high temperature performance, high temperature tensile strength and creep properties of titanum base alloys available heretofore have been less than desirable.

Accordingly, it is an object of this invention to provide improved titanium base alloys.

It is another object of this invention to provide a titanium base alloy having improved high temperature properties.

Still another object of this invention is to provide titanium base alloys having improved high temperature stress-stability properties.

How these and other objects of this invention are accomplished will become apparent in light of the accompanying disclosure.

A titanium base alloy in accordance with this invention consists essentially of about 75-85% by weight aluminum, about 9.5-l0.5% by weight vanadium, the balance being titanium. The titanium making up the balance of the alloy is substantially pure titanium, such as commercial grade purity titanium, comprising only a very minor amount of incidental impurities. These incidental impurities in the aggregate usually do not amount to more than about 0.3% by weight of the alloy composition and usually include oxygen, normally in an amount not greater than about 0.1%, nitrogen, normally in an amount not greater than about 0.05%, and carbon, normally in an amount not greater than about 0.05%. Hydrogen is also sometimes found as an impurity, normally in an amount not greater than about 0.01%.

Although a titanium base alloy in accordance with this invention, such as an alloy containing 8% by Weight aluminum and 10% by weight vanadium, the balance being titanium, shows excellent room temperature properties and stability characteristics, as well as satisfactory short time high temperature properties and satisfactory elevated temperature stress-rupture strengths, in accordance with one embodiment and feature of this invention the elevated temperature properties of the alloy are improved by incorporating therein very minor amounts of silicon or zirconium or both silicon and zirconium. Usually, the amount of either one of these high temperature improving alloying elements, silicon or zirconium, present in any alloy is not greater than about 0.8% by weight.

The following examples are illustrative of the practice of this invention:

EXAMPLE NO. 1

A titanium base alloy melt having the composition 8.0% by weight aluminum, 10.2% by weight vanadium and 0.53% by weight silicon and containing 0.10% oxygen as an incidental impurity was prepared, forged to 1" round from a temperature of 1900" F. in one heating, and rolled to a /2" rod at 1575 F. The thus-prepared rod stock was then subjected to various heat treating conditions and the mechanical properties of the heat treated bar stock determined at various temperatures. The results of these tests are set forth in accompanying Table I:

Table I MECHANICAL PROPERTIES OF ROD STOCK AT VARIOUS TEMPERATURES AND IN VARIOUS HEAT TREATED CONDITIONS Test temp., F. Y.S. (k.s.i.), T.S. (k.s.i.) R.A., Elong., Heat treatment 2% offset percent percent in 1" 144 159 13 Ann.,1250F.,A.C.

54 12s 76 30 Ann.,1250F.,A.G.

207 217 33 s 14 7 F., W.Q.;aged, 1000 156 176 57 14 a? 1475 F., w. Q.; aged, 1000" 160 173 59 16 $15., 14 F., W. aged, 1000 79 29 exp, 475 in, W. aged, 1000 166 184 49 13 S112, 1500 R, W. aged, 1000 97 153 so 27 8%.; 15 1 1 F., W.Q.; aged, 1ooo S. 210 220 20 8 157 5 11., no; aged, 1000 F.,4

151 51 14 15'17F.,A.O.;aged 1000 1 .,4

87 152 76 25 15 7 F., A.O.;aged1000 F.,4

S .1 .solution treat ed. Ann.annea1ed.

The data set forth in Table I illustrates the exceptionally high mechanical properties obtained by this alloy both at room temperature and at 800 F.

The mechanical properties of this alloy at a tempera ture of 800 F. are also set forth in Table II together with the properties of other comparable titanium base alloys and a 17-7 PH stainless steel tested at this temperature.

4 The test results set forth in Table III, like those set forth in Table II, clearly illustrate the superior high temperature properties of a titanium base alloy prepared in accordance with this invention.

7 5 EXAMPLE NO. 2

Another melt of tatanium base alloy in accordance with this invention analyzing 8.65% by weight aluminum,

Table II HOT TENSILE PROPERTIES OF VARIOUS ALLOYS AT 800 13.

Alloy Y.S. (k.s.i.), '1.S. (k.s.l.) R.A., E10ng., Heat treatment 2% offset percent percent in 1" s A1-10.2 v-.5 s1 150 170 57 14 S.T., 1475 F., W.Q.; aged, 1000 100 173 59 10 s f, ie i n, W.Q.; aged, 1000* 100 184 40 13 F., W.Q.; aged, 1000* 5 111-215 (Jr-1.25 Fe 135 lift 31 l? 15, 5156 19.? %t?8fet 5 A1-1.5 Fe1.4 Or1.2 Mo 112 133 73 17 83;: W.Q.; aged, 1000 0 A14 v 85 105 57 1s sg 1 550; W.Q.; aged, 000 v-2.5 A1 120 132 7 W.Q.; aged, 900

4 A1-4 Mn... 90 110 4a s 1 W.Q.; aged, 900 2 Fe-Z Or2 Mo 84 120 80 20 5.12% W.Q.; aged, 900 2212551131111; a e a e 17-7 PH stainless steel 152 182 Heat treated; aged, 900 F.

The test data set forth in Table II illustrates the exceptional high temperature properties of a titanium base alloy prepared in accordance with this invention. Further, the test properties of this alloy carried out at a temperature of 1000 F. are set forth in Table III and compared with the tensile properties of other titanium base alloys and a l7-7 PH stainless steel tested at this temperature.

10.34% by weight vanadium and with the balance titanium, and containing 0.09% by weight oxygen as an incidental impurity, was forged to 1'' round from 1900 F. and rolled to /1" bar at 1575 F. The mechanical properties of samples of the resulting bar stock were then tested at various temperatures and in various heat treated Table III HOT TENSILE PROPERTIES OF VARIOUS ALLoYs AT 1000 F.

Alloy Y.S. (k.s.i.), T.S. (k.s.l.) R.A., E10ng., Heat treatment 2% offset percent 8 A110.2 v-.5 s1 105 145 79 29 S.'1., 1475 F., W.Q.; Aged, 1000 97 153 80 27 sill 2. 303)? F., W.Q,.; aged, 1000 87 152 70 15 7521 A.o.;eged, 1000 F., 4 5 A1-2.75 (Jr-1.25 Fe 79 92 82 sl l eso" F., W.Q.; aged, 900 F., 5 A11.5 Fe1.4 Cr1.2 Mo 78 112 as 40 s.T.,1000 F.,W.Q.;aged,1000 F., 0 A14 v Q. 81 71 30 sg l l szeo F., W.Q.; aged, 900 F., 73 ;.94 31 S.2Ti1,r1s750 F., W.Q.; aged, 900 F., 4 111-3 Mn 82 97 55 21 slg l ew F., W.Q.; aged, 900 F., 2 Fe-2 01-2 M0 L 25 53 9s 93 s. 'r., 1450* F., W.Q.; aged, 900 F., 8 111-2 Cb-l Ta 66 79 55 33 Milled annealed alpha alloy. iil rii aifiie'ieel 13% 47 18 Heai ii'eared; aged 900 F.

conditions. The results of these tests are set forth in accompanying Table IV:

Table IV MECHANICAL PROPERTIES OF BAR STOCK AT VARIOUS'TEMPERATURES AND IN VARIOUS HEAT TREATED oONDI IONs Sample No. Test temp. Y.S. (k.s.i.), T.S. (k.s.i.) R.A., Elong., Heat Treatment 2% ofiset percent percent in 1" 5 169. 2 183. 6 28 8 As Rolled (1575 F.). 1703 182. 7 g 29 9 Annealed, 1250 F., A.C. 156. 2 180. 9 26 8 Annealed, 1575 F., A.C. 207. 2 221.7 7, 27 8 S01. ann., 1575 F., A.G., Aged,

900'F., 10 hrs. 197.8 210.4 31 8 .801. 31111., 1575 F., A.C., aged,

' 1000 F., 8 hrs. 7 149. 8 A 173.3 63 15 S01. arm., 1575 F., 11.6., aged,

900 F., 10 hrs.

Table I VContinned CREEP TESTS-SUBJECTED TO 65,000 P.S.I. FOR 100 HRS. AT 800 F.-PULLED AT ROOM TEMPERATURE AFTER CREE]? EXPOSURE Y.S. 11.51. R.A., Elng., Sample No. Test temp. 2% ofiset T.S. (k.s.i.) percent percent in 1" Heat Treatment 4-5 .74% creep 203.0 224. 2 21 7 S01. am1., 1575 F., 11.0., aged,

900 F., hrs.

4-7 .82% creep 197.0 214. 6 24 7. 5 S01. aun., 1575 F., A.C., aged,

1000 F., 8 hrs.

4-8 83% creep 193. 5 209. 9 9. 5 Sol. aun., 1575 F., A.C., aged,

1100 F., 4 hrs.

* The specimens were pulled with discoloration on the gage length from previous creep exposure.

EXAMPLE NO. 3

Another melt of titanium base alloy in accordance conditions. The results of these tests are set forth in accompanying Table V.

Table V MECHANICAL PROPERTIES OF BARTSTOGK AT VARIOUS TEMPERATURES AND IN VARIOUS HEAT REATED CONDITIONS Y.S. (k.s.i.), R.A., Elong., Sample No. Test temp. 2% oilset T.S. (k.s.i.) percent percent in 1" Heat Treatment 172.0 188.6 21 6 As rolled (1575 F.).

172.5 185. 8 16 6 Annealed, 1250 F., A. C.

161.3 180. 6 14 6 Annealed, 1575 F., A.C.

201.8 212.7 9 4 S01. ann., 1550 F., A.C., aged,

1000 F., 8 hrs.

196.4 206. 5 9 4 S01. ann. 1550 F., 11.0., aged,

105o F'., 4 hrs.

225. 5 241. 8 l7 4 S01. a1m., 1575 F., 11.0., aged,

900 F., 10 rs.

211. 5 224.1 14 5 S01. ann., 1575 F., 11.0.; aged,

1000 E, 8 hrs.

164. 2 193.4 43 11 301. mm, 1575 E, A.C., aged,

900 F 10 hrs.

OREEP TESTS-SUBJECTED TO 65,000 R8181. FOR 100 HRS. AT 800 F;.PULLED AT ROOM TEMPERATURE FTER CREEP EXPOSURE 240. 4 6 3 soslboa ng 11757" F., A.C., aged,

. 0 s. 232. 8 7 4 So1.1a)%r.1 :E1 57ghF., A.C.; aged,

. rs. 216.6 4 a. 5 501 am, 1575" F., 11.0., Aged 1100 F., 4 hrs.

* The specimens were pulled with discoloration on the gage length from previous creep exposure.

with this invention analyzing 8.51%

aluminum,

EXAMPLE NO. 4

10.20% vanadium, 0.74% zirconium, 0.59% silicon, the

balance being titanium, together with 0.08% by weight oxygen as an incidental impurity, was prepared, forged to 1" round at 1900 F. and rolled to bar at 1575 F. Samples of this bar stock were then subjected to various tests at various temperatures and in various heat treated Samples of /8" bar stock of various titanium base a1- loys having a composition in accordance with this invention were tested at various temperatures and in various heat treated conditions. The results of these tests are set forth in accompanying Table VI:

Table VI MECHANICAL PROPERTIES OF BAR STOCK AT VARIOUS MODIFICATIONS OF Ti-8 Al-10 V ALLOY COMPOSITION AS RELATED TO HEAT TREATMENT AND TEST TEMPERATURE [Tensile properties] Actual analysis Test temp. Y.S. (k.s.l.), T.S. (k.s.i.) R.A., Elong, Heat treatment 2% offset percent percent A1 V Zr Si 7. 8 10. 0 168. 2 181.0 32 11 Ann, 1250 F., A.C. 202.6 218.9 36 8 1575 F., 11.0 aged,

900 1 10 s. 194.6 209. 9 as 10 1575 F., A.C aged,

1000 F. 8 s. 156.6 172.1 63 14 R, 11.0 aged,

900 10 s. 144. 2 164. 7 v62 15. 5 1575 F., A.C aged,

10 F., 8 s. 8. 6 10. 3 170.3 182. 7 29 9 Ann., 1250 F A C 207. 2 221. 7 27 8 1575 F., A.C aged,

900 F., 10 rs. 197. 8 210. 4 31 8 1575 F., A.O aged,

1000 F. 8 rs. 149.8 173.3 63 15 1575 F., AD aged,

. 900 F., 10 s. 8. 0 10.5 4 178.3 193.8 29 9 Ann 1250 F A O 200. 2 212. 2 19 7 157g EFAQC aged,

. s. 144.7 166.0 .54 16 1575 F. AC aged,

10 o 1 6 hrs. 8.0 10.2 .5 179.0 192.0 34 10 Ann., 1250 F., A C. 210. 0 220. 0 29 8 1575 F., 11.0.; aged,

1000 F., 4 hrs.

MECHANICAL'PROPERTIES OF BAR STOCK AT VARIOUS MODIFICATIONS OF'Ti-B Air-10 VALLOY' COMPOSITION AS RELATED TO HEAT TREATMENT AND TESTTEMPERATURE v Y 5 -[Tensile properties} 5 5 I Actual analysis Test temp. -Y.S.' s 1.), T.S. (k .s.i.) R.A., Elong, Heat treatment 2% ofi'set I percent percent Al v Zr 51 151. 150. 0 51 14 -1575 F., A.O.; aged, 7 1000 F. 4111-5.

87.0 152. 0 75 25 1575 F.. .0;: aged,

. V 1000 F., 4 hrs. 8.0 9.8 .7 H 175. 5, 192.5. 27 5 Ann.,1250". F., 11.0..

21 3.6 229.4 5 1575 F. A.C.; aged,

- 4 900 10 197. 2 213. 0 15 .5. 5 75 F., A.C aged,

- 1000 F. s s. 154.5 135.1 43 l 7 10 V 1575 F. 11.0 aged,

. 5 900 F, 10 151.2 171.8 43 12 1575 F. 11.0 ,aged, 1000 in, s s 7.3 9. 5 .5 159.7 174.1. 45 12 Arm., 1250 F., 11.0. 195.4 215.3 34 s 1575 F., 11.0., aged,

1 900 F., 10 hrs. 138.0 155.4 53 14 900.11., 10 hrs.. 9. 0 10.1 5 .5 175. 3 190.4 25 7 Ann., 1250 F., 11.0. 202.8 214.5 7 r I 25 s 1575 F., 11.0.; aged, 5 1000 F. Ghrs. 154.5 .1759 31 11 75 F., A0; aged,

1000 F., 5 hrs. 8.5 10.2 7 6 172. 5 185.8 15 5 .Ann., 1250 F., 14.0.

. 222.5 241.5 17 4 .1575F. 14.0.; aged,

. 900.F., 10 hrs. 211.5 224.1. 14 5 5 75 F., A.0.; aged,

. 1000 F. 8 hrs. 154. 2 193. 4 4a 11 1575 F., A0; aged,

- 900 hrs.

vention.

TABLE v11 I-B Al-lO V ALLOY COMPOSITIO CREEP AND CREEP-STABILITY PR IQPERTIES OF BAR STOCK AT VARIOUS MODIFICATIONS OF THE 7 [Creep tests-Subjeeted to 65,000 p.s.i. for 100 hrs. at 800F. Pulled at room ternperature-aiter creep exposure] v Actual analysis,

Creep Elong, V

' 51550 treatment 7 percent 7 r percent aged, 1000 I. 4 hrs. s01 ann 157 f0 containing about 8% by weight aluminum and about 10% by weight vanadium, exhibits excellent room temperature tensile properties with good ductility. These test data also indicate that the alloy compositions of this invention have excellent high temperature tensile properties, 5 particularly at about 800 F. The test data also indicate that the addition of not more than about 0.7% silicon improves the annealed properties of the base alloy without a loss in tensile ductility. The test data clearly set forth that this amount of silicon also improves the high temperature tensile properties of the alloy.

The test data also indicate that up to about 0.7% silicon can be present in the base alloy Without a serious drop in tensile ductility and that the addition of not more than 0.6% zirconium together with not more than 0.5% silicon to the base alloy further improves the high temperature tensile properties of the alloy at 800 F. The addition of zirconium further improves the creep resistance of the base alloy and modified only by the addition of silicon. Zirconium additions to the base alloy, however, in excess of 0.6% in conjunction with silicon additions in excess of 0.5 appear to be detrimental to the room temperature properties and stability of the particular alloy of this invention. These test data also indicate that for best high temperature tensile properties an aging treatment of about 900 F. for 10 hours is recommended after annealing the alloy at 1575 F. followed by air cooling. 30

10 Generally, it has been determined that the titanium base alloys of this invention, such as an alloy having the composition about 8% by weight aluminum, about 10% by weight vanadium, the balance being titanium with incidental impurities, is at least 15% better in ten sile properties at room temperature than any commercial bar alloy and at 800 F. this percentage increases. Further, the base alloy of this invention comprising 8% by weight aluminum, 10% by weight vanadium moditied with very minor amounts of zirconium and silicon show even greater percentage diiierences at higher temperatures up to 800 F. Also, on a strength-to-Weight basis at 800 F. the zirconium and silicon modified titanium base alloy of this invention is about twice as good as the standard grades of precipitation hardening stainless steels.

In a titanium base alloy sheet product having a composition in accordance with this invention the only commercially available titanium sheet alloy that approaches it is a beta grade alloy containing 13% vanadium, 11% chromium, 3% aluminum, the balance being titanium. The disadvantages of the beta grade titanium alloy, however, are its higher density and longer ageing times required to reach optimum properties. Further, the stability of the beta alloy at a temperature about 600 F. is questionable.

Tables VIII and 1X show the superiority in respect to certain physical properties of a titanium base alloy having a composition in accordance with this invention as compared with other titanium alloys.

Table VIII BAR PRODUCT [Ti-8 .Al-lO V] Test temp. Y.S. (lr.s.i.), 'I.S. R.A., Elong, Heat treatment 0.2% ofiset (k.s.i.) percent percent 170 180 10 Ann. 195 210 30 9 1575 F., A.C.; aged, 1000 F. 8 hrs. 20:; 220 30 8 1535 132, A.C.; aged, 900 F.,

0 S. 800 145 165 15 15%: 81 H; A.C.; aged, 1000 S. 800F 150 170 (so 14 1575 11, A.C.; aged, 900 F.,

10 hrs.

[Tl-7 Al-4 M0] R31 150 160 15 Ann. RT 175 190 12 1650" F., W.Q.; aged, 900

F.,16 hrs.

[Ti-6 Al-4V] R.'I 136 148 43 15 Ann. R.T 145 152 43 15 15%? 2E. W.Q.; aged, 900

. s. R.'I 155 164 43 16 1750 F., W.Q.; aged, 900

F., 2 hrs.

800F 98 55 15 Arm. 800F 85 57 18 1550 F. W.Q.; aged, 900

F., 24 hrs. s00F 90 72 18 1750 F., W.Q.; aged, 900

F., 2 hrs.

[Tl-4 AH Mn] RJI 133 148 16 Ann. RT 162 9 1450 F. W.Q,.; aged, 900

7 Q Talzle l X 1' SHEET PRODUCT [TL-8 .41- V] Test temp. Direction Y.S. (k.s.i.), 'I.S. Elong., Heat treatment 0.2+ offset (k.s.l.) pereent1'n2" R.T Long.-- 193.7 209.8 4.5 1520; F., 11.0.; aged, 1000F rs. Y R.T Trans 194.8 208.7 6.5 150 g F., 11.0., aged, 1000 V 0 H, S.' Y. R11 Long 202.9 225.4 4 %0F181%.C.; aged, 900 S. R.T Trans 209.6 229.2 4.5 15%0 71.0.; aged, 900

' V V TS. 800 F Long 150.7 184.3 3.5 1500 n, .40.; aged, 900

V I A F.,l0hrs..

[Ti-6 111 4 V1 m 11' Ann. 3,1 170 7 1700 F., W.Q.;. aged, 975

' F., 8 hrs.

T1-5'A12.75 (Jr-1.25 Ee] R11. 7 135 14 Ann. R.1- 6 1475 11.; W.Q.; aged, 900

' 5 5l1rs.

' [Ti-3 A143 V-11 Or (beta. al1oy)] 165.8 176.1 4' 14%0.:li[*;5.,hA.O.;-aged,850'

. lS. 164.5 182.8 '6 14 1 30.; aged, 850

S. 178.5 198.0 5 140 0 12, 71.0.; aged, 900

. l'S. 185.6 203.0 a 14 F., .o.; aged, 900 v TS. 181.8 149.6 6 14%):1%,11A.O.; aged, 850

TS. 131.5 155.1 5 14%51 1"., 11.0.; aged, 850

S- 141.2 157.2 5 14 1 11.0., aged, 900

s. 146.6 7 1400* n, 11.0.; aged, 900

7 EXAMPLE NO. 5 a A titanium base alloy melt having the composition 7.26% aluminum, 9.48% vanadium, 0.50% zirconium, 0.09% silicon, the balance being titanium with 0.09%

this composition and samples'of this bar stock were tested at various temperatures and in various heat treated con ditions. The results of these tests are set forth in ac- 45 companying Table X:

* Table X r MECHANICAL PROPERTIES OF 5/8 BAR STOCK AT VARIOUS TEMPERATURES AND IN VARIOUS HEAT TREATED CONDITIONS I Y.S. 1:31. R.A., Elong., Sample No. Test temp. 2% ofiset T.S. (k.s.1.) percent percent in 1 Heat Treatment 159. 7 174. 1 46 12 .AS rolled (1575 F.).

163.3 176.3 40 12' Annealed, 1250 F., A.O. 148.3 175.3 86 1o Annealed, 1575 F., 11.0. 196.4 216.3 34 8 S01. ann., 1575 F., A..C.; aged,

900 n, 10 hrs. 190.3 201.8 38 10 sollbgnn 1575 R, All; aged,

., s. 138.0 166. 4 63 14 set. ann., 1575 11., 11.0.; aged,

900 F., 10 hrs. 138. 5 158. 6 n 64 15 S01 ann., 1575 F., A.O.; aged,

. 1000 122, 8 hrs.

CREE]? TESTS-SUBJEOTED TO 65,000 P.S.I. FOR 100 ERS. AT 800 F.PULTIED AT ROOM TEMPERATURE AFTER CREEP EXPOSURE 3...--. .55% ereep 209.6 '33 10 r 1000F.,8hrs.

"Indicates specimens were pulled with discoloration'on gage length.

oxygen as an incidental impurity, was preparedto check the .creep properties of the zirconium modified alloy. The,

It is pointed out that because the aluminum content of this particular alloy tested analyzed relatively low about 7.25% by weightaluminum, instead of the usual 8.0%

aluminurrlfound in the nominal 8% Al, 10% V, titanium melt. bar'stock was fabricated from the alloy having 75 base alloy compositions of this invention, the overall 13 properties were slightly below the capabilities of the Ti-8Al-1OV composition. The creep properties, however, were improved by the zirconium addition but to the degree that the combination of the ziconium and silicon additions, limited to about 0.5% each, improves these properties.

EXAMPLE NO. 6

As will be apparent to those skilled in the art in the light of the foregoing disclosure many modifications, substitutions, or alterations are possible in the practice of this invention without departing from the spirit or scope thereof.

We claim:

1. A titanium base alloy consisting essentially of about 7.58.5% aluminum, about 9.5-10.5% vanadium, 0.1- silicon, about 0.l0.6% zirconium, the balance being commercial grade purity titanium.

2. A titanium base alloy consisting essentially of about 8% by weight aluminum, by weight vanadium, 0.1- 0.6% by weight silicon, the balance being commercial grade purity titanium.

3. A titanium base alloy having a composition in accordance with claim 2 wherein silicon and zirconium are present in substantially equal amounts by weight.

T axle XI Y.S. (k.s.i.), R. Elong, per- Charpyim- 2% olfset T.S. (k.s.i.) percent cent in l p(3Ct,Ofl2.i1bS Heat treatment 170. 3 182. 7 29 9 8. 5 Annealed 1250 F., A.O. 207.2 221.7 27 8 9.5 So]. ann., 1575 F., A.O.; aged,

900 F., 10 hrs. 197. 8 210.4 31 8 8 S01. 211111., 1575 F., A.C., aged,

1000 F., 8 hrs.

The test data in Table XI show that the Charpy impact properties at F. and at the high tensile levels indicated are very good for these titanium base alloys.

The titanium base alloys having compositions in accordance with this invention may be prepared by any suitable and convenient method, such as melting one or more of the master alloys making up the final alloy composition and adding the other metals thereto in the desired amounts or proportions to yield the desired alloy composition. The alloy is conveniently made by melting an admixture of two or more of master alloys making up the alloy together with sponge titanium. For example, the metal alloy constituents individually in powder, granular or fragment form can be mixed as convenient and formed into a compact mass used as an arc electrode under appropriate conditions to yield an ingot of the finished alloy. The elements making up the composition are thus melted into ingot form. Although a procedure of this type is especially etfec-tive and thus is of unusual advantage or convenience, other methods of preparation of the alloys of this invention may be employed having appropriate regard for such matters as operating convenience and the desired type or use of the product.

4. A titanium base alloy having a composition in accordance with claim 2 wherein the incidental impurities present in the titanium are not greater than about 0.3% by weight based on said alloy.

5. A titanium base alloy consisting essentially of about 8% by weight aluminum, about 10% by weight vanadium about 0.6% by weight zirconium, about 0.5% by weight silicon, the balance being commercial grade titanium.

DAVID L. RECK, Primary Examiner.

RAY K. WINDHAM, WINSTON A. DOUGLAS,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,184,305 May 18, 196E Sidney W. Poole et a1 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columns 3 and 4, Table III, first column, line 5 thereof, for "4 Al-3 Mn" read 4 Al-4 Mn columns 5 and 6, Table V, third column, second section of the table, line 3 thereof, for "201.6" read 201.4 same section of Table V, seventh column, line 1 thereof, for "1757 F. read 1575 F. same columns 5 and 6, and columns 7 and 8, Table VI, for the column heading "Y.S. (k.s.i.) 2% offset", each occurrence, read Y.S. [k.s.i.) .2% offset column 8, line 33, for "iindicates" read indicates columns 9 and 10, Table VIII for the column heading "Y.S. (k.s.i.), 0.2% offset" read Y.S. (k.s.i.) offset column 10, line 25, for "about" read above columns 11 and 12, Table IX, for the column heading "Y.S. (k.s.i.), 0.2+ offset" read Y.S. (1 .s.i.), .2% offset same Table IX, fourth column, line 5 thereof, for "184.3" read 184.4 column 11, line 75, for "5/8 bar stock" read 5/8 bar stock column 14 line 13, before "silicon" insert zirconium, 0.10.5% by weight line 45, for "Crossley" read Crossley et a1.

Signed and sealed this 30th day of November 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A TITANIUM BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT 7.5-8.5% ALUMINUM, ABOUT 9.5-10.5% VANDIUM, 0.10.5% SILICON, ABOUT 0.1-0.6% ZIRCONIUM, THE BALANCE BEING COMMERCIAL GRADE PURITY TITANIUM 